The present invention generally relates to soldering. More specifically, the present invention relates to soldering a wire to a terminal pin with a noncontacting heat source.
It is generally known to contact the terminal pins to the winding ends of coils, e.g., relay coils, by immersion of the pins respectively wound with the winding ends in a solder bath. However, with this method, a fluxing agent is required in order to assure reliable soldering.
Unfortunately, fluxing agents and solder baths release toxic vapors. Furthermore, fluxing agent residues can damage neighboring contact surfaces. In the relay, for instance, such damage can cause an outage of the relay during later operation. Moreover, traditional solder baths have operating temperatures of approximately 350.degree. C. and are, therefore, subject to pronounced scaling of their surface resulting in great quantities of waste solder.
In an effort to eliminate the need for undesirable fluxing agents, it is known to fuse winding ends to respective terminal pins with are welding under a protective atmosphere (hereinafter referred to as "TIG" welding). Such a method is disclosed in German published application 2 063 535. Under certain circumstances, however, the high welding temperatures subject the associated coil to an excessively high thermal load.
Also, U.S. Pat. No. 4,039,801 (which claims priority based on German published application 2 301 094) relates to the use of a pre-tinplated terminal pin in a process of arc welding a section of wound wire thereto. A layer of solder is provided on the pin. The solder, however, is used to position the wire. The permanent contacting is the result of welding at a high welding temperature.
Therefore, a need exists for an improved method of soldering a winding end to a terminal pin without the use of a fluxing agent. Furthermore, a need exists for such a method which avoids high welding temperatures with the corresponding thermal load.